Interpretive Summary: Plants of the Brassica family (mustards) are vegetables commonly consumed in the U.S. These plants have received considerable attention in recent years because they contain glucosinolates, phenolic compounds, and fiber, all health-promoting compounds. Members of the Brassica family (oleracea) consist of broccoli, cabbage, and cauliflower. We recently published a survey of the phenolic content of three of this group, kale, collard greens, and Chinese broccoli. This work reported here is complementary, examining the phenolic content of some of the non-oleracea members of the Brassicas (mustard greens, yu choy, and 15 other vegetables). It is shown that the phenolic profiles of the non-oleracea species differ from those of B. olerecea. Seventy-one different phenolic acids and glycosylated flavonoids were identified, ten of these for the first time in these vegetables. These data expand our knowledge of the phytochemical content of these vegetables and promote the evaluation of their impact on human health.

Technical Abstract:
A liquid chromatography-mass spectrometry (LC-MS) profiling method was used to characterize the phenolic components of 17 leafy vegetables from Brassica species other than Brassica oleracea. The vegetables studied were mustard green, baby mustard green, gai choy, baby gai choy, yu choy, yu choy tip, bok choy, bok choy tip, baby bok choy, bok choy sum, Taiwan bok choy, Shanghai bok choy, baby Shanghai bok choy, rapini broccoli, turnip green, napa, and baby napa. This work led to the tentative identification of 71 phenolic compounds consisting of kaempferol 3-O-diglucoside-7-O-glucoside derivatives, isorhamnetin 3-O-glucoside-7-O-glucoside hydroxycinnamoyl gentiobioses, hydroxycinnamoylmalic acids, and hydroxycinnamoylquinic acids. Ten of the compounds, 3-O-diacyltriglucoside-7-O-glucosides of kaempferol and quercetin, had not been previously reported. The phenolic component profiles of these vegetables were significantly different than those of the leafy vegetables from B. oleracea. This is the first comparative study of these leafy vegetables. Ten of the vegetables had never been previously studied by LC-MS.